Go 5 Ammonia, Sulphuric Acid, Nitric Acid

8/2/2019 Go 5 Ammonia, Sulphuric Acid, Nitric Acid

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Ammonia

Ammonia is a compound of nitrogen and hydrogen with the formula

NH3.

It is a colourless gas with a characteristic pungent odour.

Ammonia contributes significantly to the nutritional needs of terrestrial

organisms by serving as a precursor to food and fertilizers.

Ammonia, either directly or indirectly, is also a building block for the

synthesis of many pharmaceuticals. Although in wide use, ammonia is both caustic and hazardous. It is

used in commercial cleaning products.

Ammonia is produced industrially by the Haber-Bosch process which

involves the catalytic reduction of nitrogen (obtained by fractional

distillation from liquid air) by hydrogen at temperatures of 450-500 C

and pressures of 35-40 MPa.

Preparatio

Properties Uses


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AMMONIA

Preparation of Ammonia

Ammonia is produced industrially by the Haber-Bosch process which involves the

catalytic reduction of nitrogen (obtained by fractional distillation from liquid air) by

hydrogen at temperatures of 450-500 C and pressures of 35-40 MPa.

This is achieved by increasing the pressure on the reacting system. In practice,

the pressure that is used is around 40 MPa (about 400 times normal atmospheric

pressure).


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Synthesis gas preparation

First, the methane is cleaned, mainly toremove sulfur oxide and hydrogen sulfide impuritiesthat would poison the catalysts.

The clean methane is then reacted with steam overa catalyst of nickel oxide. This is called steamreforming:CH4 + H2O CO + 3 H2

Secondary reforming then takes place with theaddition of air to convert the methane that did notreact during steam reforming.2 CH4 + O2 2 CO + 4 H2CH4 + 2 O2 CO2 + 2H2O

Then the water gas shift reaction yields morehydrogen from CO and steam.CO + H2O CO2 + H2

The gas mixture is now passed into amethanator[8] which converts most of theremaining CO into methane for recycling:CO + 3 H2 CH4 + H2O

This last step is necessary as carbonmonoxide poisons the catalyst. The overallreaction so far turns methane and steaminto carbon dioxide, steam, and hydrogen.


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Ammonia synthesis Haber process

The final stage, which is the actual Haber process, is the synthesis ofammonia using an iron catalyst promoted with K2O, CaO and Al2O3:

N2 (g) + 3 H2 (g) 2 NH3 (g) (H = 92.22 kJmol1)

This is done at 1525 MPa (150250 bar) and between 300 and550 C, passing the gases over four beds of catalyst, with coolingbetween each pass to maintain a reasonable equilibrium constant.

The steam reforming, shift conversion, carbon dioxide removal, andmethanation steps each operate at absolute pressures of about 2.53.5 MPa (2535 bar), and the ammonia synthesis loop operates at

absolute pressures ranging from 618 MPa (60180 bar), dependingupon which proprietary design is used.


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Properties of

Ammonia

soluble in water

combines with water to

form ammonium

hydroxide

Boiling point is

33.35 C (28.03

F), and its freezing

point is 77.7 C

(107.8 F)

colourless gas with a

sharp, penetrating

odour


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Uses ofAmmonia

FertilizerPrecursor tonitrogenouscompounds

Cleaner

Fermentation

Refrigeration R717

As a fuelFor

remediationof gaseous

emissions

Antimicrobialagent for

foodproducts

As astimulant

used fortreatmentof cottonmaterials

used to fillweatherballoons

as a liftinggas

to darkenquartersawnwhite oak inArts & Craftsand Mission

style furniture


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SULPHURIC ACID

Sulphuric

Sulfuric acid is a strong mineral acid with the molecular

formula H2SO4. Its historical name is oil of vitriol.

Pure sulfuric acid is a highly corrosive, colorless, viscous liquid.

The salts of sulfuric acid are called sulfates. Sulfuric acid is soluble

in water at all concentrations.

Sulfuric acid has many applications, and is a central substance in

the chemical industry.

Principal uses include lead-acid batteries for cars and other

vehicles, ore processing, fertilizer manufacturing, oil

refining, wastewater processing, and chemical synthesis.

Sulphuric acid industrially produced by using Contact Process

Preparation Properties Uses


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The contact process is the current method of producingsulfuric acidin the high

concentrations needed for industrial processes. Vanadium(V) oxide is the

catalystemployed.

The process can be divided into three stages:

Preparation and purification ofsulfur dioxide

Catalytic oxidation (usingvanadium oxide catalyst) of

sulphur dioxide to sulfurtrioxide

Conversion of sulphur trioxideto sulphuric acid

Preparation
http://en.wikipedia.org/wiki/Sulfuric_acidhttp://en.wikipedia.org/wiki/Sulfuric_acidhttp://en.wikipedia.org/wiki/Sulfuric_acidhttp://en.wikipedia.org/wiki/Vanadium%28V%29_oxidehttp://en.wikipedia.org/wiki/Vanadium%28V%29_oxidehttp://en.wikipedia.org/wiki/Catalysthttp://en.wikipedia.org/wiki/Catalysthttp://en.wikipedia.org/wiki/Catalysthttp://en.wikipedia.org/wiki/Vanadium%28V%29_oxidehttp://en.wikipedia.org/wiki/Sulfuric_acid


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Purification of air and SO2 is

necessary to avoid catalyst poisoning(ie. removing catalytic activities).

The gas is then washedwith water and dried by

H2SO4.

To conserve energy, the mixture isheated by exhaust gases from the

catalytic converter by heatexchangers.

Sulphur dioxide and oxygen then react inthe manner as follows:

2SO2(g) + O2(g) 2 SO3(g): H= 197kJ mol1

To increase the reaction rate, hightemperatures (450 C), high pressures (200

kPa or 2 atm), and vanadium(V) oxide(V

2

O5

) are used to ensure a 99.5%conversion. Platinum would be a moresuitable catalyst, but it is very costly and

easily poisoned.


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A flow scheme for this part of the process looks like above.

Making thesulphur dioxide

This can either bemade by burningsulphur in an excess ofair:

. . . or by heatingsulphide ores likepyrite in an excess ofair:

In either case, anexcess of air is used

so that the sulphurdioxide produced isalready mixed withoxygen for the next

stage.

Converting thesulphur dioxide into

sulphur trioxide

This is a reversiblereaction, and theformation of the

sulphur trioxide isexothermic..


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Converting the sulphur

trioxide into sulphuric acid

This can't be done by simply adding waterto the sulphur trioxide - the reaction is souncontrollable that it creates a fog ofsulphuric acid.

Instead, the sulphur trioxide is firstdissolved in concentrated sulphuric acid:

H2SO4 + SO3 H2SO7

The product is known asfumingsulphuric acidor oleum.

H2SO7 + H2O 2H2SO4


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Properties

Propertiesof H2SO4

powerfulprotonating

agent.

moderatelystrong oxidizin

g agent.

powerful

dehydratingagent

strong dibasicacid

powerfuldehydrating

agent

colourless,

hygroscopicliquid

no odour


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Uses ofH2SO4

electrolyte usedin lead-acid

batteries(accumulators)

production offertilizers such asammonium sulfate

(sulfate ofammonia which isformed when rock

phosphate istreated withsulfuric acid.

remove oxidesfrom iron and steelbefore galvanisingor electroplating

Concentratedsulfuric acid (18M)

is used as adehydrating agent,that is, to removewater, since it has

a tendency to formhydrates such as

H2SO4.H2O,H2SO4.2H2O, etc.

used in theproduction of

nitroglycerine, aninorganic ester &

organic nitrate

used as a dryingagent to

chemically removewater from many

substances.


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NITRIC ACID

Nitric Acid, HNO3

Nitric acid (HNO3, also known as aqua fortisand spirit of nitre, is a

highly corrosive and toxic strong acid.

Colorless when pure, older samples tend to acquire a yellow cast due to

the accumulation of oxides of nitrogen.

If the solution contains more than 86% nitric acid, it is referred to

as fuming nitric acid.

Depending on the amount of nitrogen dioxide present, fuming nitric

acid is further characterized as white fuming nitric acid or red fuming

nitric acid, at concentrations above 95%.

Nitric acid is also commonly used as a strong oxidizing agent.

Preparation Properties Uses


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Preparation of Nitric Acid

Nitric acid is made by reaction of nitrogen dioxide (NO2) with water.

3 NO2 + H2O 2 HNO3 + NO

Normally, the nitric oxide produced by the reaction is reoxidized by the oxygen in

air to produce additional nitrogen dioxide

Bubbling nitrogen dioxide through hydrogen peroxide can help to improve acid

yield.

2 NO2 + H2O2 2 HNO3

Almost pure nitric acid can be made by adding sulfuric acid to a nitrate salt, and

heating the mixture with an oil bath. A condenser is used to condense the nitric

acid fumes that bubble out of the solution.

2 NaNo3 + H2SO4 2 HNO3 + Na2SO4

Ostwald Process
http://en.wikipedia.org/wiki/Sulfuric_acidhttp://en.wikipedia.org/wiki/Sulfuric_acid


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Ostwald Process

Production of nitric acid is via the Ostwald Process, named after German

chemist Wilhem Ostwald.

Further concentration to 98% can be achieved by dehydration with

concentrated H2SO4. By using ammonia derived from the Haber process, the final

product can be produced from nitrogen, hydrogen, and oxygen which are derived

from air and natural gas as the sole feedstocks.

In this process, anhydrous ammonia is oxidized to nitric oxide, in the presenceof platinum or rhodium gauge catalyst at a high temperature of about 500K and apressure of 9 bar.

4 NH3 (g) + 5 O2(g) 4 NO (g) + 6 H2O (g) (H = 905.2 kJ)

Nitric oxide is then reacted with oxygen in air to form nitrogen dioxide.

2 NO (g) + O2(g) 2 NO2(g) (H = 114 kJ/mol)

This is subsequently absorbed in water to form nitric acid and nitric oxide.

3 NO2 (g) + H2O (l) 2 HNO3(aq) + NO (g) (H = 117 kJ/mol)

The nitric oxide is cycled back for reoxidation. Alternatively, if the last step is carriedout in air:

4 NO2 (g) + O2 (g) + 2 H2O (l) 4 HNO3 (aq)

The aqueous HNO3 obtained can be concentrated by distillation up to about 68%by mass.
http://en.wikipedia.org/wiki/Sulphuric_acidhttp://en.wikipedia.org/wiki/Sulphuric_acidhttp://en.wikipedia.org/wiki/Sulphuric_acidhttp://en.wikipedia.org/wiki/Sulphuric_acidhttp://en.wikipedia.org/wiki/Sulphuric_acidhttp://en.wikipedia.org/wiki/Haber_processhttp://en.wikipedia.org/wiki/Haber_processhttp://en.wikipedia.org/wiki/Sulphuric_acid


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Properties ofnitric acid

colorless mobileliquid with a

density of 1.512g/cm3

In liquid state

Transparent to

yellow

As gaseous oxides

Transparent to

yellow or brown

Odour

Sweet to pungent

strong oxidizingagent

both acidic andbasic properties it

can undergo anautoprotolysis

reaction, similar tothe self-ionization

of water

reacts violentlywith many organicmaterials and thereactions may be

explosive.

reacts with mostmetals


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Uses of nitric acid

It is used in the

production ofammonium nitrate for

fertilizers.

It is used for makingplastics

It is used in themanufacture of dyes

used for makingexplosives such as

nitroglycerine

When it is combined

with hydrochloric acid itforms an element called

aqua regia which is areagent that is capableof dissolving gold and

platinum.

used in a colorimetrictest to distinguish heroin

and morphine.

commonly used inscience laboratories at

schools forexperimenting whenspecifically testing for

chloride.

used in the field ofmedicine in its pure stateas a caustic to get rid of

chancres and warts.

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